Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

medical microbiology test 2 > Lecture 9 > Flashcards

Lecture 9 Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards USMLE® Step 1 flashcards
1
Q

4 postulates of the classical version

A
  • The suspected pathogenic organism should be present in ALL cases of the disease and absent from healthy animals. Done by microscopy or/and gram staining.
  • The suspected organism should be grown in pure culture via laboratory culture
  • Cells of a pure culture of the suspected organism should cause disease in a healthy animal via using experimental animals
  • The organism should be re-isolated and shown to be the same as the original via laboratory re-isolation.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Is the classical four postulate rule always true?

A

 The “gold standard” in medical microbiology, but it is not always possible to satisfy all postulates for every infectious disease.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Molecular Postulates

A
  • The gene or its products should be found only in strains which cause disease
  • Genes should be isolated by cloning
  • Disruption of the gene should reduce or attenuate its virulence
  • Gene is expressed by bacterium at some point during infection
  • Elimination of the disease causing microbe or prevention should eliminate or prevent disease. Examples:
  • Antibiotic therapy
  • Improvements in sanitation to prevent cholera
  • Treatment of H. pylori
  • Vaccination approaches (Streptococcus pneumoniae).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Ferrets are used for testing what disease

A

H. pylori

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Guinea pig is used for testing what disease

A

TB

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Aramadillo is used for testing what disease

A

Leprosy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Chinchillas is used for testing what diseas

A
  • H. influenza
  • S. pneumo
  • ear infections
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Rabbit is used for testing what disease

A

Ocular infections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Zebra Fish is used for testing what diseas

A

Streptococci, necrotizing fasciitis and mycobacterium infections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Sample animal model

A

 Infect with bacteria
 Treat or monitor response
 Sacrifice and plate bacteria for CFU

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

LD50

A

refers to 50% lethal dose; referring to dose where 50% of animals are moribund

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

ID50

A

refers to 50% infectious dose; referring to the number of bacteria required to infect 50% of the animals.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Competition assay

A

 Is a way to make LD50 and ID50 experiments more sensitive

 In these experiments mutants and the wild-type compete for resources, including colonization sites.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

To cause disease, Microorganisms must

A

 Find and enter the host
 Colonize the host
 Resist host defense
 Cause damage to, or cause malfunction of host tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Portals of Entry include

A
  • Ingestion
  • Respiratory
  • Wounds
  • Sexually transmitted
  • Medically transmitted
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Ingestion of microorganisms

A

 Fecal-oral

 Contaminated food or water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Ingestion of microorganisms causes:

A

GI disease

Oral Disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

respiratory portal of microorganisms

A

 Aerosols

 Contaminated hands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Wound portal of microorganisms

A
  • scratches

- Bites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Sexually transmitted portal of microorganisms

A

STD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Medically Transmitted microorganisms as portal of entry

A
  • Catheter

- Contact lenses

22
Q

Pili

A

specific adhesion; often involves lectins

23
Q

Type 4 pili

A

twitching motility

24
Q

Capsule

A
  • form of adhesion
  • Non specific adhesion
  • protection
25
Q

M protein of what is a type of adhesion

A

Streptococcus

26
Q

Examples of importance of adhesion causing disease/colonization

A
  • UTI by non piliated E. coli is not able to attach to host tissue producing mild symptoms
  • Pilliated gonococci attached more compared to non piliated
27
Q

Factors involved in Colonization (adhesins) give example of each

A
  • Anatomic (pregnancy UTI)
  • Metabolic (diabetes)
  • Neoplastic (cancer)
  • Therapeutic (anti-rejection drugs, radiation)
  • Ischemia (tissue death due to loss of blood)
  • Substance abuse (contaminated needles)
  • Primary infection (opportunistic infection)
28
Q

Resisting host defense

A

1) Loss of ag
2) Overproduction of bacterial ag bind to host ab (super antigen)
3) Capsule binds with serum protein H (host ag) and inhibit complement activation.
4) b-altered bacterial ag (antigenic variation)
5) mimic of host antigen (molecular mimicry)
6) Resisting Antibiotics (immunoglobulins)

29
Q

example of b-altered bacterial ag (antigenic variation)

A

Salmonella use this technique to switch between different types of protein flagellin

30
Q

H. pylori LPS O antigen contains carbohydrates similar to host is an example of what?

A

mimic of host antigen (molecular mimicry)

31
Q

Protein A of S. aureus and Protein G of S. pyogenes binds with Fc region and prevent opsonization
 Ig protease
 Bind host material
an example of what?

A

Resisting Antibiotics (immunoglobulins)

32
Q

Bacteria taken up into phagosome however phagosome does not become acidified meaning it does not fuse with lysosome. Phagosome surrounded by endoplasmic reticulum studded with ribosomes. Bacteria multiply in phagosomes and phagosomes ruptures. Host cell lyses and bacteria is released. What is an example of bacteria that does this?

A

L. pneumophila

33
Q

Bacteria binds CR3 on the surface of the macrophage; bacteria is taken up in the vesicle. Bacteria recruits host proteins to surface of phagosomes again no fusion of lysosomes and phagosomes. Bacteria prevent endocytic acidification; have reduced oxidative burst and bacteria replicate. An example of such bacteria is?

A

Mycobacteria

34
Q

Escape from phagosome and cell-cell spread

A

 Evades phagolysosomal fusion after internalization by escaping the phagosome through secretion of listeriolysin O (LLO) and two phospholipases, PlcA and PlcB.
 Once in the cytoplasm, L. monoctogenes replicates and becomes motile by using actin ‘comet tails’ generated by the effector ActA.
 LLO functional at pH 5.5 it creates pores in phagosomal membranes as early as 5 minutes.

35
Q

 Penetration Strategies- Salmonella and Shigella

A

 Salmonella serovar Thyphimurium delivers effector proteins into host cells to protect vacuole and evade host response.
 Phagolysosomal maturation is stalled and vacuoles do not contain mannose-6-phosphate receptor and lysosomal hydrolytic enzymes.

36
Q

function of fibrinolysin?

A

degrades blood clots

37
Q

How do microorganisms get around Lactoferrin, transferrin?

A

Bacteria have sideophores and Fe acquistion

38
Q

how do bacteria/microorganisms get around adverse pH, low nutrients in host

A
  • have habitat selection

- use alternative nutrients

39
Q

Type 1 toxins

A

bind to targets at the cell surface and are not translocated into the cell.

40
Q

Super antigen is what type of toxin

A

Type I

41
Q

Super antigen

A

 Superantigens (Sag) that affect macrophages and T cells altering their functions and causing copious cytokinesis release; super antigens greatly enhance T-cell stimulation.
 Super antigen forms a bridge complex between MHC molecules on antigen presenting cells and T-cell receptors which in turn over stimulate T-cells to release cytokines resulting in toxic shock.

42
Q

Endotoxins like Staphylococus aureus are what type of toxin? and cause what?

A
  • Type I toxin
  • Toxic shock syndrome
  • responsible for tampon recall
43
Q

Type II toxin

A

act on the cell membranes; membrane disruption

44
Q

Type II toxins include:

A

 Phospholipids
 Pore-forming cytotoxins like Mycolactone
 Phospholipase C and hemolysins remove the polar head group and destabilize the membrane

45
Q

Type III toxins are

A

Typically A-B toxins

46
Q

About type III toxins

A

Typically A-B toxins
 carry two functional components:
An enzyme domain (A) that inactivates some intracellular target
And a binding component (B) that recognizes a surface receptor and mediates the uptake of the A component.

 The simplest A-B toxins is synthesized as single polypeptide chains

 These domains are separated during processing by proteolysis

 The detachment of A from B is necessary for optimal activity of A.

47
Q

Toxin Export

A

 Toxins are produced in the cytoplasm but act externally
 Protein secretion mechanisms
 General secretory system (sec)
 Types I-VII secretion; export systems varies with organism and toxin.

48
Q

General secretory System (sec)

A

 Occurs in G+ and G-
 Protein synthesized with 15-26 a signal sequence (leader peptide)
 After export, signals peptidase cleaves signal sequence

49
Q

Secretory systems specific to gram negatives

A
  • T2SS, T5SS are sec dependent

- T1SS, T3SS, T4SS, TGSS are sec independent

50
Q

Secretory systems specific to gram positives

A
  • Cytolysin mediate tanslocation (CMT) such as streptolysin O
  • Ex portal example B. Subtillis
51
Q

T7SS

A

Mycobacteria

medical microbiology test 2 (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions